Method for Control of the Degree of Branch of Polybutadiene with High 1,4-CIS Content

Abstract

A method for controlling the degree of branching of a 1,4-cis polybutadiene when preparing the 1,4-cis polybutadiene from 1,3-butadiene monomers in a nonpolar solvent using a catalyst system containing a an organonickel compound, alkylaluminum compound, and a boron fluoride complex is carried out by controlling the catalyst combination and a pretreatment condition. The method allows easy control of the degree of branching of the 1,4-cis polybutadiene without having to control the polymerization temperature or to add additional additives. As a result, the processability and the physical properties of the polymer can be optimized.

1 . A method for controlling a degree of branching of a 1,4-cis polybutadiene in preparing a 1,4-cis polybutadiene by polymerizing butadiene monomers in the presence of a catalyst system of an organonickel compound, an aluminum compound and a boron fluoride complex, comprising:
 sequentially adding the organonickel compound, the boron fluoride complex, and the aluminum compound to a polymerization reactor without aging; or adding one of the organonickel compound, the boron fluoride complex, and the aluminum compound to a polymerization reactor without aging and adding the other two to the polymerization reactor after aging at −20 to 60° C.   
     
     
         2 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein a molar ratio of the organonickel compound, the aluminum compound, and the boron fluoride complex is 1:1-20:0.7-50. 
     
     
         3 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein the organonickel compound is one or more selected from the group consisting of nickel hexanoate, nickel heptanoate, nickel octanoate, nickel 2-ethylhexanoate, nickel naphthenate, nickel versatate, nickel 1,2-cyclohexanediamino-N,N′-bis(3,5-t-butylsalicylidene), nickel hexamethylacetylacetonate, and nickel stearate. 
     
     
         4 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein the aluminum compound is one or more selected from the group consisting of trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, and diisobutylaluminum hydride. 
     
     
         5 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein the boron fluoride complex is a complex of boron trifluoride (BF 3 ) with one or more selected from the group consisting of an ether compound, a ketone compound, and an ester compound. 
     
     
         6 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 5 , wherein:
 the ether compound is selected from dimethyl ether, diethyl ether, dibutyl ether, tetrahydrofuran, dihexyl ether, dioctyl ether, and methyl t-butyl ether;   the ketone compound is one or more selected from the group consisting of acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; and   the ester compound is selected from methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate and ethyl ethoxypropionate.   
     
     
         7 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein, in the polymerization, one or more selected from the group consisting of a C 4 -C 10  aliphatic hydrocarbon, a C 5 -C 10  cyclic aliphatic hydrocarbon, and a C 6 -C 10  aromatic hydrocarbon is used as a solvent. 
     
     
         8 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 7 , wherein:
 the C 4 -C 10  aliphatic hydrocarbon is selected from butane, pentane, hexane, heptanes, and octane;   the C5-C10 cyclic aliphatic hydrocarbon is one or more selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, and cyclooctane; and   the C 6 -C 10  aromatic hydrocarbon is selected from benzene, toluene and xylene.   
     
     
         9 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein the aging of the catalyst is performed by pretreating in a catalyst aging solvent at −20 to 60° C. for 5 minutes to 2 hours. 
     
     
         10 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 9 , wherein the catalyst aging solvent is one of cyclohexane, hexane, heptanes, and toluene. 
     
     
         11 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein the polymerization is performed at 20-100° C. for 1-12 hours. 
     
     
         12 . The method for controlling the degree of branching of a 1,4-cis polybutadiene according to  claim 1 , wherein the degree of branching calculated from the ratio of solution viscosity (cps)/Mooney viscosity (M 1+4 , 100° C.) is 7-13. 
     
     
         13 . A method for controlling a degree of branching of a 1,4-cis polybutadiene, comprising:
 in preparing a 1,4-cis polybutadiene by polymerizing butadiene monomers in the presence of a catalyst system of an organonickel compound, an aluminum compound and a boron fluoride complex, one of:
 sequentially adding the organonickel compound, the boron fluoride complex, and the aluminum compound to a polymerization reactor without aging; and 
 adding one of the organonickel compound, the boron fluoride complex, and the aluminum compound to a polymerization reactor without aging and adding the other two to the polymerization reactor after aging at −20 to 60° C.